In telecommunications, measuring, signal processing and control engineering the requirement of separating wanted and unwanted signals comes up again and again. In most cases the stipulated requirements can be fulfilled by the use of known passive or active linear filters such as low-pass, high-pass, band pass filters and the like. Depending on their order and the selection of their adjustment parameters, for instance according to the rules of Butterworth, Chebyshev or Bessel, it is thereby possible to produce in known manner certain properties of their amplitude/frequency characteristics, e.g. with respect to residual ripple in the pass range, steepness of decay to the stop band and so forth. In a manner also known, with the selection of the amplitude characteristic there is singularly established at the same time also an associated phase response, where the phase loss increases with increasing frequency also with the filter order and steepness of decay to the stop band and is not negligible, in particular also in the useful range. When such filters are used in such feedback systems as control loops, phase-locked loops and the like, the phase/frequency response connected with the desired amplitude/frequency response often has an adverse effect on other indispensable requirements such as stability and signal-to-noise ratio.